RE: ferric oxalate
On Mon, 10 Nov 2008, EJN Photo wrote:
Eric and company: What do you know about the keeping qualities of chemicals in general when they're bought in bulk but not used right away? I recently, for instance, threw out a large hunk of ferric ammonium citrate because it had turned into just that -- a really hard, solid hunk.... The cost does go down very fast AFTER the quantity of raw chemicals goes up a bit. If you just get 500 g of Ferrous Ammonium Sulfate, that might be around $65 but a 2.5 Kg is only $ 105 or so and 25kg is cheaper still. Artcraft might be able to repackage it if enough people wanted to get some.
It could have been 5 years old, but was well packaged (tightly wrapped in supposedly air and water tight plastic)... Anyway, I was suprised.
Now there's talk of, for instance, 60 pound supply of whatever -- would you use, say a pound a month? That could still be 5 years... On the one hand, I'm using an old supply of ammonium dichromate, maybe 30 or 50 years old, and it seems fine... but on the other, there was that FAC. Is there any general info on the topic ? Is it reliable ?